eɪ.ˈtɪp.ɪ.kəl ɪˈɹɛɡjəlɚ deviating from normal expectations; somewhat odd, strange, or abnormal these days large families are atypical atypical clinical findings atypical pneumonia highly irregular behavior not representative of a group, class, or type a class of atypical mosses atypical behavior is not the accepted type of response that we expect from children